Difference between revisions of "Synthesis of Organic Semiconductors"

Latest revision as of 07:44, 17 March 2010

Design criteria

HOMO/LUMO levels and bandgap

-Controlled by type of conjugated system, electron donating/electron withdrawing groups

Solid state packing/self-assembly

-Presence and position of substituents

Solubility

-Introduction of substituents

Volatility

Ease of synthesis

HOMO/LUMO level control

The conjugation length determines homo lumo levels.

The HOMO increases in energy with increasing conjugation length.
The LUMO decreases in energy with increasing conjugation length.
The band gap (Eg) is decreases with increasing conjugation length.
Polymer is more susceptible to electrophiles because of its higher HOMO. ie. more reactive.

Effect of electron donating and electron withdrawing substituents

Electron donating groups increase the energy levels.

Electron withdrawing groups decrease the energy levels.

Effect of polymer structure

Twists in the structure generally decrease the effective conjugation length and therefore increase the bandgap.

Substituents

Bulky substituents will increase solubility making the material easier to process.

However, in the solid state, bulky substituents will disrupt the packing of molecules/polymers therefore decreasing charge mobility through materials.

The substituent often has to be altered through trial and error to obtain material with the appropriate HOMO/LUMO levels, solubility, and optoelectronic performance.

P-type small molecule/oligomer synthesis

Examples of p-type molecules: Pentacene

Excellent TFT performance Best TFTs give > 5 cm2/(V s), ION/IOFF = 106

Insoluble: Devices fabricated by vacuum sublimation

Pentacene is oxygen and light-sensitive

Efforts to solubilize pentacene: Silyl modified pentacene

Silyl modified pentacene

Solution processed TFTs: > 5 cm2/(V s)

see Anthony 2001^[1]

see Park 2006 ^[2]

Soluble precursor approach

Combines best of both worlds by providing material that is soluble, but has good packing once solubilizing group is removed.

OTFTs

μ = 0.1 cm2 / V⋄s

I_ON / I_OFF = 2 x 10⁵

see Weidkamp 2004 ^[3] see Afzali 2002 ^[4]

Examples of p-type molecules: Oligothiophenes

Introduce substituents to * position to provide solubility

Dihexylsexithiophene

Packing aided by liquid crystalline-like behavior of alkyl chains Sparingly soluble in hot organic solvents

see Lovinger 1998^[5]

Soluble precursor route

Precursor is highly soluble in organic solvents
Heating burns off the solubilizing groups, anneals thiophenes into terraced structures

OTFTs: μ= 0.05 cm2 / V⋄s; I_ON / I_OFF = 10⁵ after thermal treatment

see Murphy 2004 ^[6]

N-type small molecule/oligomer synthesis

N-type materials

Most organic materials are p-type.

Two procedures are generally used to make a material n-type.
-Decrease LUMO level of material by introducing electron withdrawing groups eg. naphthalene derivatives

naphthalene derivatives

-Decrease LUMO level by introducing strain eg. C60 derivatives

Error creating thumbnail: Unable to save thumbnail to destination

C60

Examples of n-type molecules

Aromatic bis-imides

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One of the early organic n-FET successes.

see Katz 2000 ^[7]

Error creating thumbnail: Unable to save thumbnail to destination

see Würthner 2004 ^[8]

Fluorinated pentacene

Fluorinated pentacene synthesis

μ = 0.22 cm²/Vs and I_on/I_off =10⁵

see Sakamoto 2004 ^[9].

C60 derivatives

Error creating thumbnail: Unable to save thumbnail to destination

PCBM

Phenyl C60 Butyric Acid Methyl Ester (PCBM)

Error creating thumbnail: Unable to save thumbnail to destination

ThCBM

Thienyl CBM (ThCBM)

See Lacramioara 2006 ^[10]

Single precursor p & n-type material

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N-type OTFT μ = 0.08 cm²/Vs and Ion/I_off =10⁶

P-type OTFT μ = 2 × 10^-4 cm2/Vs and I_on/I_off =10⁴

see Yoon 2007 ^[11]

Review of polymers

Step growth vs. Chain growth polymerizations

Step growth

Broad molecular weights

Molecular weight is heavily dependent on the purity of the monomer
Leads to batch-to-batch variability
Optoelectronic properties vary which means fluctuating electronic device performance

Chain growth

One monomer at a time adds to the growing polymer chain.
Under certain conditions, the polymerization can be controlled to produce specific molecular weights with narrow polydispersities (living polymerization)

Molecular weights of polymers

The Number average molecular weight:

The Weight average molecular weight:

The Polydispersity Index:

Small molecule vs. Polymer semiconductors

Small molecules have well-defined molecular weights which lends itself better to provide crystalline packing.

Polymers generally contain amorphous domains which reduces charge transport.

Polymers are more amenable to room temperature solution processing. Although both small molecules and polymers can be solubilized, polymers tend to make smoother, more continuous films.

Semiconducting polymers

Semiconductivity in polymers can be achieved in two ways:

1) By having pendant small molecule semiconductors attached onto an insulating polymer backbone.

2) By having a conjugated polymer.

Polymers with pendant groups tend to show poorer charge mobility because it is difficult to organize the polymer such that the pendant groups stack well.

But, easier to perform a controlled polymer synthesis on polymers with pendant groups using, for example, ATRP, ROMP, and NMRP.

Common conjugated polymers

P-type polymer synthesis

Polythiophenes

Historical progression of polythiophenes

For comprehensive review on polythiophenes: ^[12]

Initially, conjugated polymers were synthesized by oxidative coupling reactions.

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But oxidative coupling can lead to defects. Eg. instead of the required 2,2 coupling, 2,3 coupling can also take place.

Dehalogenation routes were also attempted.

Better than oxidative coupling because 2,3 coupling can be avoided.

However, both routes still suffer when solubilizing groups are added.

Regiorandom polymers end up being synthesized when a regioregular HT-HT polymer is desirable.

By differentiating the two ends of the substituted thiophene, which can be done cleanly, it is possible to do a cross coupling reaction and thereby synthesize truly regioregular polyalkylthiophenes.

Error creating thumbnail: Unable to save thumbnail to destination

see McCullough method: ^[13]

see Rieke method: ^[14]

Improving on regioregular poly(3-hexylthiophene) (P3HT)

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Poor TFT performance when devices are fabricated in air. (I_OFF high due to O₂ doping)

μ = 0.15 cm² / V⋅s

I_ON/I_OFF = 10⁷

Stable in air for >30d

see Ong 2004 ^[15]

Fused ring polythiophenes

see Heeney 2005 ^[16]

More p-type polymers: Polyphenylenevinylenes (PPV)

Synthesized via soluble precursor route

see Wessling 1985 ^[17]

see Wessling 1972
Wessling, 1968 (?!), US Patent 3,401,152 and 1972, US Patent 3,706,677

Soluble PPV

a) 3-(bromomethyl)heptane, KOH, C2H5OH, reflux b) formaldehyde, conc. HCl, dioxane c) KOC(CH3)3, THF

a) 3-(bromomethyl)heptane, KOH, C2H5OH, reflux

b) formaldehyde, conc. HCl, dioxane

c) KOC(CH3)3, THF

See Wudl 1991 ^[18]

More p-type polymers: Polyfluorenes

Polyfluorene: Originally synthesized in 1989 see Fukuda 1989 ^[19]

see ^[20]

Polyfluorenes: obtained blue polymer for LEDs

Originally, the emission at approx. 550 nm was thought to be a results of aggregation.

Bulky substituents were added to polyfluorene to reduce green emission and create “blue” polymer.

see JACS ^[21]

see List and Scherf ^[22]

But it was realized that the red-shifted emission was due to keto defects within the polymer.

Polymer design was altered so that there would be a silicon bridge rather than a carbon bridge to prevent keto defects from forming.

see Chan and Holmes ^[23]

N-type polymer synthesis

N-type polymers

This is rare but growing area of research.

Highly ordered Lamellar packing

μ = 0.10−0.16 cm²/(V s), Ion/I_off = 10⁷ Devices stable in air for >5 months

see Usta 2008^[24]

see Babel and Jenekhe 2003 ^[25]

Napthalene based polymers

μ = 0.01 cm²/VS

see JACS ^[26]

Ambipolar polymers

μh = 10-3 cm2/(V s) μe = 10-2 cm2/(V s)

see Kim and Jenekhe 2009 ^[27]

Controlled polymer synthesis

Metal catalyzed cross-coupling polymerizations

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The majority of conjugated polymers are synthesized via metal catalyzed cross-coupling reactions eg. Ni mediated reactions is shown.

P3HT synthesis

P3HT synthesis was originally thought to occur via a step-growth polymerization.

When Ni(0) reductively eliminates, it can in theory reinsert into any Ar-Br bond. If this were to occur, this would be a step-growth polymerization

But McCullough and Yokozawa found that the resulting polymer had a narrow PDI and controlled molecular weight, which means that it is likely to be a chain-growth polymerization.

P3HT synthesis

dppp>dppe>dppf>PPh3

Polymerization is heavily ligand dependent and works best if dppp is used as the ligand.

Narrow PDI
MW proportional to Ni loading

Associated pair

Key step: Ni(0) only adds into the same growing polymer chain resulting in chain-growth polymerization

see McCullough ^[28]

see Miyakoshi ^[29]

Externally initiated P3HT synthesis

TM = transmetallation RE = reductive elimination OA = oxidative addition

Restricted to only being able to use PPh3 as a ligand. dppp gives H/Br polymer.

see Doubina and Luscombe 2009 ^[30]

see van Leeuwen 2000 ^[31]

Adapting to ligands other than PPh3

A novel method for the external initiated polymerizations of P3HT has developed by CMDITR researchers. The method produces a polymer with a well-defined molecular weight, narrow polydispersity index (PDI), 100% initiation efficiency, 100% regioregularity. This work represents the most control achieved for the synthesis of P3HT.

see Bronstein and Luscombe 2009 ^[32]

References

↑ J. E. Anthony; J. S. Brooks; D. L. Eaton; S. R. Parkin; J. Am. Chem. Soc. 2001, 123, 9482-9483.
↑ S. J. Park; C. C. Kuo; J. E. Anthony; T. N. Jackson; Tech. Dig. − Int. Electron Devices Meet. 2006, 113.
↑ Weidkamp, K. P.; Afzali, A.; Tromp, R. M.; and Hamers, R. J. J. Am. Chem. Soc., 2004, 126, 12740.
↑ Afzali, A.; Dimitrakopoulos, C. D.; Breen, T. L. J. Am. Chem. Soc., 2002, 124, 8812.
↑ A. J. Lovinger; H. E. Katz; A. Dodabalapur Chem. Mater., 1998, 10, 3275.
↑ A. R. Murphy; J. M. J. Fréchet; P. Chang; J. Lee; V. Subramanian J. Am. Chem. Soc., 2004, 126, 1596.
↑ Katz, H. E.; Lovinger, A. J.; Johnson, J.; Kloc, C.; Slegrist, T.; Li, W.; Lin, Y. Y.; Dodabalapur, A. Nature 2000, 404, 478
↑ F. Würthner; V. Stepanenko; Z. Chen; C. R. Saha-Möller; N. Kocher; D. Stalke J. Org. Chem. 2004, 69, 7933.
↑ Y. Sakamoto; T. Suzukil; M. Kobayashi; Y. Gao; Y. Fukai; Y. Inoue; F. Sato; S. Tokito J. Am. Chem. Soc., 2004, 126, 8138–8140
↑ Lacramioara M. Popescu, Patrick van 't Hof, Alexander B. Sieval, Harry T. Jonkman, and Jan C. Hummelen Appl. Phys. Lett. 89 213507 (2006)
↑ M.-H. Yoon; S. A. DiBenedetto; M. T. Russell; A. Facchetti; T. J. Marks Chem. Mater., 2007, 19, 4864–4881.
↑ R. D. McCullough, Adv. Mater. 1998, 10, 93
↑ J. Chem. Soc. Chem. Commun. 1992, 70-72
↑ J. Am. Chem. Soc. 1992, 114, 10087
↑ B. S. Ong; Y. Wu.; P. Liu; S. Gardner, J. Am. Chem. Soc., 2004, 126, 3378.
↑ M. Heeney; C. Bailey; K. Genevicius; M. Shkunov; D. Sparrowe; S. Tierney; I. McCulloch J. Am. Chem. Soc., 2005, 127, 1078-1079.
↑ Wessling, J. Polym. Sci. Polym. Symp. 1985, 72, 55
↑ Wudl et al. ACS Symp. Ser, 1991, 455; US Patent 1990, 5,189,136
↑ Fukuda et al. Jpn. J. Appl. Phys. 28, L1433, 1989
↑ Adv. Funct. Mater. 15, 981, 2005
↑ J. Am. Chem. Soc., 123, 6965, 2001
↑ List and Scherf et al. Adv. Mater. 14, 374, 2002
↑ Chan and Holmes et al. J. Am. Chem. Soc. 127, 7662, 2005.
↑ H. Usta; A. Facchetti; T. J. MarksJ. Am. Chem. Soc., 2008, 130, 8580.
↑ A. Babel and S. A. Jenekhe J. Am. Chem. Soc., 2003, 125, 13656.
↑ JACS, 2009, 8-9.
↑ F. S. Kim and S. A. Jenekhe et al. Adv. Mater., Vol. 21, P. 1-5, 2009
↑ McCullough, Macromolecules 2004, 37, 3526
↑ Miyakoshi and Yokozawa et al., J. Am. Chem. Soc. 2005, 127, 17542
↑ Doubina and Luscombe, Macromolecules, 2009, 42, 7670
↑ van Leeuwen et al. Chem. Rev. 2000, 100, 2741
↑ H. Bronstein, C. K. Luscombe, J. Am. Chem. Soc., 2009, 131, 12894

[1] J. E. Anthony; J. S. Brooks; D. L. Eaton; S. R. Parkin; J. Am. Chem. Soc. 2001, 123, 9482-9483.

[2] S. J. Park; C. C. Kuo; J. E. Anthony; T. N. Jackson; Tech. Dig. − Int. Electron Devices Meet. 2006, 113.

[3] Weidkamp, K. P.; Afzali, A.; Tromp, R. M.; and Hamers, R. J. J. Am. Chem. Soc., 2004, 126, 12740.

[4] Afzali, A.; Dimitrakopoulos, C. D.; Breen, T. L. J. Am. Chem. Soc., 2002, 124, 8812.

[5] A. J. Lovinger; H. E. Katz; A. Dodabalapur Chem. Mater., 1998, 10, 3275.

[6] A. R. Murphy; J. M. J. Fréchet; P. Chang; J. Lee; V. Subramanian J. Am. Chem. Soc., 2004, 126, 1596.

[7] Katz, H. E.; Lovinger, A. J.; Johnson, J.; Kloc, C.; Slegrist, T.; Li, W.; Lin, Y. Y.; Dodabalapur, A. Nature 2000, 404, 478

[8] F. Würthner; V. Stepanenko; Z. Chen; C. R. Saha-Möller; N. Kocher; D. Stalke J. Org. Chem. 2004, 69, 7933.

[9] Y. Sakamoto; T. Suzukil; M. Kobayashi; Y. Gao; Y. Fukai; Y. Inoue; F. Sato; S. Tokito J. Am. Chem. Soc., 2004, 126, 8138–8140

[10] Lacramioara M. Popescu, Patrick van 't Hof, Alexander B. Sieval, Harry T. Jonkman, and Jan C. Hummelen Appl. Phys. Lett. 89 213507 (2006)

[11] M.-H. Yoon; S. A. DiBenedetto; M. T. Russell; A. Facchetti; T. J. Marks Chem. Mater., 2007, 19, 4864–4881.

[12] R. D. McCullough, Adv. Mater. 1998, 10, 93

[13] J. Chem. Soc. Chem. Commun. 1992, 70-72

[14] J. Am. Chem. Soc. 1992, 114, 10087

[15] B. S. Ong; Y. Wu.; P. Liu; S. Gardner, J. Am. Chem. Soc., 2004, 126, 3378.

[16] M. Heeney; C. Bailey; K. Genevicius; M. Shkunov; D. Sparrowe; S. Tierney; I. McCulloch J. Am. Chem. Soc., 2005, 127, 1078-1079.

[17] Wessling, J. Polym. Sci. Polym. Symp. 1985, 72, 55

[18] Wudl et al. ACS Symp. Ser, 1991, 455; US Patent 1990, 5,189,136

[19] Fukuda et al. Jpn. J. Appl. Phys. 28, L1433, 1989

[20] Adv. Funct. Mater. 15, 981, 2005

[21] J. Am. Chem. Soc., 123, 6965, 2001

[22] List and Scherf et al. Adv. Mater. 14, 374, 2002

[23] Chan and Holmes et al. J. Am. Chem. Soc. 127, 7662, 2005.

[24] H. Usta; A. Facchetti; T. J. MarksJ. Am. Chem. Soc., 2008, 130, 8580.

[25] A. Babel and S. A. Jenekhe J. Am. Chem. Soc., 2003, 125, 13656.

[26] JACS, 2009, 8-9.

[27] F. S. Kim and S. A. Jenekhe et al. Adv. Mater., Vol. 21, P. 1-5, 2009

[28] McCullough, Macromolecules 2004, 37, 3526

[29] Miyakoshi and Yokozawa et al., J. Am. Chem. Soc. 2005, 127, 17542

[30] Doubina and Luscombe, Macromolecules, 2009, 42, 7670

[31] van Leeuwen et al. Chem. Rev. 2000, 100, 2741

[32] H. Bronstein, C. K. Luscombe, J. Am. Chem. Soc., 2009, 131, 12894

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[5]

[6]

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[8]

[9]

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[11]

[12]

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[17]

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[19]

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@@ Line 1: / Line 1: @@
+<table id="toc" style="width: 100%">
+<tr>
+<td style="text-align: left; width: 33%">[[Organic Electronics Overview|Previous Topic]]</td>
+<td style="text-align: center; width: 33%">[[Main_Page#Organic Electronics|Return to Organic Electronics Menu]]</td>
+<td style="text-align: right; width: 33%">[[Organic Field Effect Transistors|Next Topic]]</td>
+</tr>
+</table>
 == Design criteria ==
@@ Line 54: / Line 63: @@
 Insoluble: Devices fabricated by vacuum sublimation
-Pentacene is oxygen and light sensitive
+Pentacene is oxygen and light-sensitive
 <br clear='all'>
 === Efforts to solubilize pentacene: Silyl modified pentacene ===
 [[Image:Silyl_pentacene.png|thumb|500px|Silyl modified pentacene]]
@@ Line 83: / Line 93: @@
 === Examples of p-type molecules: Oligothiophenes ===
+[[Image:Oligothiophene_solubility.png|thumb|300px|Introduce substituents to * position to provide solubility
+]]
+<br clear='all'>
+[[Image:Dihexylsexithiophene.jpg|thumb|300px|Dihexylsexithiophene]]
-Introduce substituents to * position to provide solubility
-Dihexylsexithiophene
 Packing aided by liquid crystalline-like behavior of alkyl chains
-Sparingly soluble in �hot organic solvents
+Sparingly soluble in hot organic solvents
 see Lovinger 1998<ref>A. J. Lovinger; H. E. Katz; A. Dodabalapur Chem. Mater., 1998, 10, 3275.</ref>
+<br clear='all'>
 === Soluble precursor route ===
+[[Image:Soluble_precursor_oligo.png|thumb|500px|]]
+*Precursor is highly soluble in organic solvents
+*Heating burns off the solubilizing groups, anneals thiophenes into terraced structures
-Precursor is highly soluble in organic solvents
+OTFTs: &mu;= 0.05 cm2 / V⋄s; I<sub>ON</sub> / I<sub>OFF</sub> = 10<sup>5</sup> after thermal treatment
-Heating burns off the solubilizing groups, anneals thiophenes into terraced structures
-OTFTs: = 0.05 cm2 / V⋄s; ION / IOFF = 105 after thermal treatment
 see Murphy 2004 <ref>A. R. Murphy; J. M. J. Fréchet; P. Chang; J. Lee; V. Subramanian J. Am. Chem. Soc., 2004, 126, 1596.</ref>
 == N-type small molecule/oligomer synthesis ==
@@ Line 110: / Line 119: @@
 Two procedures are generally used to make a material n-type.
+<br clear='all'>
+-Decrease LUMO level of material by introducing electron withdrawing groups eg. naphthalene derivatives
--Decrease LUMO level of material by introducing electron withdrawing groups eg. naphthalene derivatives
+[[Image:Napthalene_derivatives.png|thumb|300px|naphthalene derivatives]]
 -Decrease LUMO level by introducing strain eg. C60 derivatives
+[[Image:C60.png|thumb|300px|C60]]
+<br clear='all'>
 === Examples of n-type molecules===
 ==== Aromatic bis-imides ====
+[[Image: Aromaticbisamide.png|thumb|200px|]]
 One of the early organic n-FET successes.
-Katz, H. E.; Lovinger, A. J.; Johnson, J.; Kloc, C.; Slegrist, T.; Li, W.; Lin, Y. Y.; Dodabalapur, A.  Nature 2000, 404, 478
+see Katz 2000 <ref>Katz, H. E.; Lovinger, A. J.; Johnson, J.; Kloc, C.; Slegrist, T.; Li, W.; Lin, Y. Y.; Dodabalapur, A.  Nature 2000, 404, 478</ref>
+<br clear='all'>
+[[Image:Aromaticbisamide2.png|thumb|300px|]]
+see Würthner 2004 <ref>F. Würthner; V. Stepanenko; Z. Chen; C. R. Saha-Möller; N. Kocher; D. Stalke J. Org. Chem. 2004, 69, 7933.</ref>
+====Fluorinated pentacene ====
-F. Würthner; V. Stepanenko; Z. Chen; C. R. Saha-Möller; N. Kocher; D. Stalke J. Org. Chem. 2004, 69, 7933.
+[[Image:Fluorinated_pentacene.png|thumb|500px|Fluorinated pentacene synthesis]]
-====Fluorinated pentacene ====
+&mu; = 0.22 cm<sup>2</sup>/Vs and I<sub>on</sub>/I<sub>off</sub> =10<sup>5</sup>
-see Y. Sakamoto; T. Suzukil; M. Kobayashi; Y. Gao; Y. Fukai; Y. Inoue; F. Sato; S. Tokito J. Am. Chem. Soc., 2004, 126, 8138–8140.
+see Sakamoto 2004 <ref>Y. Sakamoto; T. Suzukil; M. Kobayashi; Y. Gao; Y. Fukai; Y. Inoue; F. Sato; S. Tokito J. Am. Chem. Soc., 2004, 126, 8138–8140</ref>.
+<br clear='all'>
 ==== C60 derivatives ====
+[[Image:PCBM.png|thumb|300px|PCBM]]
 Phenyl C60 Butyric Acid Methyl Ester
 (PCBM)
+<br clear='all'>
+[[Image:ThCMBM.png|thumb|300px|ThCBM]]
 Thienyl CBM (ThCBM)
-HCBM: Lacramioara M. Popescu, Patrick van 't Hof, Alexander B. Sieval, Harry T. Jonkman, and Jan C. Hummelen
+See Lacramioara 2006 <ref>Lacramioara M. Popescu, Patrick van 't Hof, Alexander B. Sieval, Harry T. Jonkman, and Jan C. Hummelen
 Appl. Phys. Lett. 89 213507 (2006)
+</ref>
 === Single precursor p & n-type material ===
-N-type OTFT  = 0.08 cm2/Vs and Ion/Ioff =106
+[[Image:Precursor_p&n.png|thumb|300px|]]
-P-type OTFT  = 2 × 10-4 cm2/Vs and Ion/Ioff =104
+N-type OTFT &mu; = 0.08 cm<sup>2</sup>/Vs and Ion/I<sub>off</sub> =10<sup>6</sup>
-M.-H. Yoon; S. A. DiBenedetto; M. T. Russell; A. Facchetti; T. J. Marks Chem. Mater., 2007, 19, 4864–4881.
+P-type OTFT &mu; = 2 × 10<sup>-4</sup> cm2/Vs and I<sub>on</sub>/I<sub>off</sub> =10<sup>4</sup>
+see Yoon 2007 <ref>M.-H. Yoon; S. A. DiBenedetto; M. T. Russell; A. Facchetti; T. J. Marks Chem. Mater., 2007, 19, 4864–4881.</ref>
 == Review of polymers ==
 === Step growth vs. Chain growth polymerizations ===
+<br clear='all'>
 Step growth
+[[Image:Stepgrowth.gif|thumb|200px|Step growth ]]
 Broad molecular weights
@@ Line 159: / Line 184: @@
 *Leads to batch-to-batch variability
 *Optoelectronic properties vary which means fluctuating electronic device performance
+<br clear='all'>
+Chain growth
+[[Image:Chaingrowth.gif|thumb|200px|Chain growth ]]
-Chain growth
 *One monomer at a time adds to the growing polymer chain.
 *Under certain conditions, the polymerization can be controlled to produce specific molecular weights with narrow polydispersities (living polymerization)
+=== Molecular weights of polymers ===
+[[Image:Polymer_mw.png|thumb|300px|]]
-=== Molecular weights of polymers ===
+The Number average molecular weight:
+:<math>M_n = \frac {\sum_i N_i M_i} {\sum_i N_i}\,\!</math>
+The Weight average molecular weight:
+:<math>M_w = \frac {\sum_i N_i M_i^2} {\sum_i N_i M_i}\,\!</math>
+The Polydispersity Index:
+:<math>PDI = \frac {M_w} {M_n}\,\!</math>
+<br clear='all'>
 === Small molecule vs. Polymer semiconductors ===
@@ Line 181: / Line 219: @@
 === Semiconducting polymers ===
 Semiconductivity in polymers can be achieved in two ways:
+[[Image:Semeconduct_backbone.png|thumb|200px|]]
+) By having pendant small molecule semiconductors attached onto an insulating polymer backbone.
+<br clear='all'>
+[[Image:Conjugated_polymer.png|thumb|300px|]]
+) By having a conjugated polymer.
-*By having pendant small molecule semiconductors attached onto an insulating polymer backbone.
-*By having a conjugated polymer.
 *Polymers with pendant groups tend to show poorer charge mobility because it is difficult to organize the polymer such that the pendant groups stack well.
-*But, easier to perform a controlled polymer synthesis on polymers with pendant groups using, for example, ATRP, ROMP, and NMRP.
+*But, easier to perform a controlled polymer synthesis on polymers with pendant groups using, for example, ATRP, ROMP, and NMRP.
+<br clear='all'>
 === Common conjugated polymers ===
+[[Image:Conjugated_polymer_common.png|500px|]]
+<br clear='all'>
 == P-type polymer synthesis ==
 === Polythiophenes ===
-For comprehensive review on polythiophenes: R. D. McCullough, Adv. Mater. 1998, 10, 93
+[[Image:Polythiophenes_history.png|thumb|center|600px|]]
+Historical progression of polythiophenes
+For comprehensive review on polythiophenes: <ref>R. D. McCullough, Adv. Mater. 1998, 10, 93</ref>
-Historical progression of polythiophenes
+<br clear='all'>
 Initially, conjugated polymers were synthesized by oxidative coupling reactions.
+[[Image:Polythiophene_coupling.png|thumb|500px|]]
 But oxidative coupling can lead to defects. Eg. instead of the required 2,2 coupling, 2,3 coupling can also take place.
+[[Image:Polythiophene_coupling_defect.png|thumb|300px|]]
+<br clear='all'>
 Dehalogenation routes were also attempted.
+[[Image:Polythiophene_dehalogenation.png|thumb|300px|]]
+<br clear='all'>
 Better than oxidative coupling because 2,3 coupling can be avoided.
@@ Line 211: / Line 264: @@
 Regiorandom polymers end up being synthesized when a regioregular HT-HT polymer is desirable.
+[[Image:Regiorandom_polymer.png|thumb|500px|]]
+<br clear='all'>
+By differentiating the two ends of the substituted thiophene, which can be done cleanly, it is possible to do a cross coupling reaction and thereby synthesize truly regioregular polyalkylthiophenes.
+[[Image:Regioregular.png|thumb|500px|]]
-By differentiating the two ends of the substituted thiophene, which can be done cleanly, it is possible to do a cross coupling reaction and thereby synthesize truly regioregular polyalkylthiophenes.
+[[Image:Regioregular2.png|thumb|400px|]]
+see McCullough method: <ref>J. Chem. Soc. Chem. Commun. 1992, 70-72</ref>
-McCullough method: J. Chem. Soc. Chem. Commun. 1992, 70-72
+see Rieke method: <ref>J. Am. Chem. Soc. 1992, 114, 10087</ref>
-Rieke method: J. Am. Chem. Soc. 1992, 114, 10087
-Improving on regioregular poly(3-hexylthiophene) (P3HT)
+=== Improving on regioregular poly(3-hexylthiophene) (P3HT)===
+[[Image:P3ht_unit.png|thumb|200px|]]
 Poor TFT performance when devices are fabricated in air.
-(IOFF high due to O2 doping)
+(I<sub>OFF</sub> high due to O<sub>2</sub> doping)
-B. S. Ong; Y. Wu.; P. Liu; S. Gardner, J. Am. Chem. Soc., 2004, 126, 3378.
+[[Image:P3ht_lamellar.png|thumb|500px|]]
+&mu; = 0.15 cm<sup>2</sup> / V⋅s
+I<sub>ON</sub>/I<sub>OFF</sub> = 10<sup>7</sup>
+Stable in air for >30d
+see Ong 2004 <ref>B. S. Ong; Y. Wu.; P. Liu; S. Gardner, J. Am. Chem. Soc., 2004, 126, 3378.
+</ref>
+<br clear='all'>
 === Fused ring polythiophenes ===
+[[Image:Fusedring.png|thumb|center|500px|]]
+see Heeney 2005 <ref>M. Heeney; C. Bailey; K. Genevicius; M. Shkunov; D. Sparrowe; S. Tierney; I. McCulloch J. Am. Chem. Soc., 2005, 127, 1078-1079.</ref>
-M. Heeney; C. Bailey; K. Genevicius; M. Shkunov; D. Sparrowe; S. Tierney; I. McCulloch J. Am. Chem. Soc., 2005, 127, 1078-1079.
+=== More p-type polymers: Polyphenylenevinylenes (PPV) ===
+[[Image:Ppv.png|thumb|500px|]]
 Synthesized via soluble precursor route
-Wessling, J. Polym. Sci. Polym. Symp. 1985, 72, 55
-Wessling, 1968 (?!), US Patent 3,401,152 and 1972, US Patent 3,706,677
+see Wessling 1985 <ref>Wessling, J. Polym. Sci. Polym. Symp. 1985, 72, 55</ref>
+see Wessling 1972 <br clear='all'>Wessling, 1968 (?!), US Patent 3,401,152 and 1972, US Patent 3,706,677
 === Soluble PPV ===
+[[Image:Ppv_soluble.png|thumb|500px|a) 3-(bromomethyl)heptane, KOH, C2H5OH, reflux
+b) formaldehyde, conc. HCl, dioxane
+c) KOC(CH3)3, THF]]
--(bromomethyl)heptane, KOH, C2H5OH, reflux
+a) 3-(bromomethyl)heptane, KOH, C2H5OH, reflux
-formaldehyde, conc. HCl, dioxane
-KOC(CH3)3, THF
-Wudl et al. ACS Symp. Ser, 1991, 455; US Patent 1990, 5,189,136
+b) formaldehyde, conc. HCl, dioxane
+c) KOC(CH3)3, THF
+See Wudl 1991 <ref>Wudl et al. ACS Symp. Ser, 1991, 455; US Patent 1990, 5,189,136</ref>
+<br clear='all'>
 === More p-type polymers: Polyfluorenes ===
+[[Image:Polyfluorene.jpg|thumb|300px|]]
 Polyfluorene: Originally synthesized in 1989
-Fukuda et al. Jpn. J. Appl. Phys. 28, L1433, 1989
+see Fukuda 1989 <ref>Fukuda et al. Jpn. J. Appl. Phys. 28, L1433, 1989</ref>
-Adv. Funct. Mater. 15, 981, 2005
+[[Image:Polyfluorene_all.jpg|thumb|500px|]]
-=== More p-type polymers: Polyphenylenevinylenes (PPV) ===
+see <ref>Adv. Funct. Mater. 15, 981, 2005</ref>
+<br clear='all'>
+=== Polyfluorenes: obtained blue polymer for LEDs ===
+[[Image:Polyfluorene_synth.jpg|thumb|500px|]]
+Originally, the emission at approx. 550 nm was thought to be a results of aggregation.
+Bulky substituents were added to polyfluorene to reduce green emission and create “blue” polymer.
-=== Polyfluorenes: obtained blue polymer for LEDs ===
+[[Image:Polyfluorene_spec.jpg|thumb|400px|]]
-Originally, the emission at approx. 550 nm was thought to be a results of aggregation.
+see JACS <ref>J. Am. Chem. Soc., 123, 6965, 2001</ref>
-Bulky substituents were added to polyfluorene to reduce green emission and create “blue” polymer.
-J. Am. Chem. Soc., 123, 6965, 2001
+[[Image:Polyfluorene_synth2.jpg|thumb|400px|]]
-List and Scherf et al. Adv. Mater. 14, 374, 2002
+see List and Scherf <ref>List and Scherf et al. Adv. Mater. 14, 374, 2002</ref>
+[[Image:Polyfluorene_synth3.jpg|thumb|400px|]]
 But it was realized that the red-shifted emission was due to keto defects within the polymer.
+[[Image:Polyfluorene_synth4.jpg|thumb|400px|]]
 Polymer design was altered so that there would be a silicon bridge rather than a carbon bridge to prevent keto defects from forming.
-Chan and Holmes et al. J. Am. Chem. Soc. 127, 7662, 2005.
+[[Image:Polyfluorene_spec2.jpg|thumb|300px|]]
+see Chan and Holmes <ref>Chan and Holmes et al. J. Am. Chem. Soc. 127, 7662, 2005.</ref>
+<br clear='all'>
 == N-type polymer synthesis ==
@@ Line 278: / Line 365: @@
 === N-type polymers ===
-Rare but growing area of research.
+This is rare but growing area of research.
-Highly ordered Lamellar packing
+[[Image:N-type.png|thumb|500px|Highly ordered Lamellar packing]]
-μ = 0.10−0.16 cm2/(V s), Ion/Ioff = 107
-Devices stable in air for >5 months
-H. Usta; A. Facchetti; T. J. Marks
+μ = 0.10−0.16 cm<sup>2</sup>/(V s), Ion/I<sub>off</sub> = 10<sup>7</sup>
-J. Am. Chem. Soc., 2008, 130, 8580.
+Devices stable in air for >5 months
+[[Image:Ladder.png|thumb|500px|]]
+see  Usta 2008<ref>H. Usta; A. Facchetti; T. J. MarksJ. Am. Chem. Soc., 2008, 130, 8580.</ref>
+see Babel and Jenekhe 2003 <ref>A. Babel and S. A. Jenekhe J. Am. Chem. Soc., 2003, 125, 13656.</ref>
+<br clear='all'>
+=== Napthalene based polymers ===
-=== A. Babel and S. A. Jenekhe J. Am. Chem. Soc., 2003, 125, 13656.
+[[Image:Napthalene_polymer_synth.png|thumb|500px|&mu; = 0.01 cm<sup>2</sup>/VS]]
-Napthalene based polymers ===
-JACS, 2009, 8-9.
+see JACS <ref>JACS, 2009, 8-9.</ref>
+<br clear='all'>
 === Ambipolar polymers ===
-F. S. Kim and S. A. Jenekhe et al. Adv. Mater., Vol. 21, P. 1-5, 2009
+[[Image:Ambipolar.png|thumb|500px|]]
+μh = 10-3 cm2/(V s)
+μe = 10-2 cm2/(V s)
+see Kim and Jenekhe 2009 <ref>F. S. Kim and S. A. Jenekhe et al. Adv. Mater., Vol. 21, P. 1-5, 2009</ref>
+<br clear='all'>
 == Controlled polymer synthesis ==
 === Metal catalyzed cross-coupling polymerizations ===
-The majority of conjugated polymers are synthesized via metal catalyzed cross-coupling reactions eg. Ni mediated reactions is shown below.
+[[Image:Crosscoupling.png|thumb|400px|]]
+The majority of conjugated polymers are synthesized via metal catalyzed cross-coupling reactions eg. Ni mediated reactions is shown.
 === P3HT synthesis ===
+[[Image:P3ht_synth.png|thumb|500px|P3HT synthesis]]
 P3HT synthesis was originally thought to occur via a step-growth polymerization.
 When Ni(0) reductively eliminates, it can in theory reinsert into any Ar-Br bond. If this were to occur, this would be a step-growth polymerization
+But McCullough and Yokozawa found that the resulting polymer had a narrow PDI and controlled molecular weight, which means that it is likely to be a chain-growth polymerization.
+[[Image:P3ht_synth2.png|thumb|500px|P3HT synthesis]]
+dppp>dppe>dppf>PPh3
+Polymerization is heavily ligand dependent and works best if dppp is used as the ligand.
+*Narrow PDI
+*MW proportional to Ni loading
+Associated pair
+Key step: Ni(0) only adds into the same growing polymer chain resulting in chain-growth polymerization
+see McCullough <ref>McCullough, Macromolecules 2004, 37, 3526</ref>
+see Miyakoshi <ref>Miyakoshi and Yokozawa et al., J. Am. Chem. Soc. 2005, 127, 17542</ref>
+<br clear='all'>
 === Externally initiated P3HT synthesis ===
+[[Image:P3ht_synth_ext.png|thumb|500px|]]
+[[Image:P3ht_synth_ext2.png|thumb|500px|]]
+<br clear='all'>
 TM = transmetallation
 RE = reductive elimination
@@ Line 322: / Line 438: @@
 Restricted to only being able to use PPh3 as a ligand. dppp gives H/Br polymer.
-Doubina and Luscombe, Macromolecules, 2009, 42, 7670
+see Doubina and Luscombe 2009 <ref>Doubina and Luscombe, Macromolecules, 2009, 42, 7670</ref>
+<br clear='all'>
+[[Image:P3ht_synth_ext_ligand.png|thumb|300px|]]
+see van Leeuwen 2000 <ref>van Leeuwen et al. Chem. Rev. 2000, 100, 2741</ref>
+<br clear='all'>
+=== Adapting to ligands other than PPh3 ===
+[[Image:P3ht_synth_regioregular.png|thumb|500px|]]
-adapting to ligands other than PPh3
 A novel method for the external initiated polymerizations of P3HT has developed by CMDITR researchers. The method produces a polymer with a well-defined molecular weight, narrow polydispersity index (PDI), 100% initiation efficiency, 100% regioregularity. This work represents the most control achieved for the synthesis of P3HT.
-H. Bronstein, C. K. Luscombe, J. Am. Chem. Soc., 2009, 131, 12894
+see Bronstein and Luscombe 2009 <ref>H. Bronstein, C. K. Luscombe, J. Am. Chem. Soc., 2009, 131, 12894</ref>
 == References ==
 <references/>

Difference between revisions of "Synthesis of Organic Semiconductors"

Latest revision as of 07:44, 17 March 2010

Design criteria

HOMO/LUMO level control

Effect of electron donating and electron withdrawing substituents

Effect of polymer structure

Substituents

P-type small molecule/oligomer synthesis

Examples of p-type molecules: Pentacene

Efforts to solubilize pentacene: Silyl modified pentacene

Soluble precursor approach

Examples of p-type molecules: Oligothiophenes

Soluble precursor route

N-type small molecule/oligomer synthesis

N-type materials

Examples of n-type molecules

Aromatic bis-imides

Fluorinated pentacene

C60 derivatives

Single precursor p & n-type material

Review of polymers

Step growth vs. Chain growth polymerizations

Molecular weights of polymers

Small molecule vs. Polymer semiconductors

Semiconducting polymers

Common conjugated polymers

P-type polymer synthesis

Polythiophenes

Improving on regioregular poly(3-hexylthiophene) (P3HT)

Fused ring polythiophenes

More p-type polymers: Polyphenylenevinylenes (PPV)

Soluble PPV

More p-type polymers: Polyfluorenes

Polyfluorenes: obtained blue polymer for LEDs

N-type polymer synthesis

N-type polymers

Napthalene based polymers

Ambipolar polymers

Controlled polymer synthesis

Metal catalyzed cross-coupling polymerizations

P3HT synthesis

Externally initiated P3HT synthesis

Adapting to ligands other than PPh3

References

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